Your heart

Your heart is about the same size as a pear. It sits behind your ribs on the left side of your body just next to your sternum.

It has four parts, the left ventricle (say ven-trik-ul) and the right ventricle which are both at the bottom of the heart, and the left atrium (say ay-tree-um) and the right atrium at the top. A wall of muscle called the septum separates them.

The walls of the heart are made of really strong muscles that squeeze and relax to pump blood around the body.

It does this about 90 times a minute if you're a child and 70 times a minute if you are an adult.

Blood is pushed from the atriums into the ventricles on each side of the heart.

Between them, small valves open and shut with each heartbeat so the blood can only flow in one direction.

The left side of the heart gets the blood from the lungs where it has collected oxygen, and pushes it all round the body through the arteries and the tiny blood vessels called capillaries (say cap-il-a-rees). This blood is a bright red colour.

The right side of the heart gets the blood after it has taken oxygen round the body and sends it back to the lungs for some more oxygen. This blood is carrying carbon dioxide (say car-bon dye-ox-eye-d), which gets breathed out when it reaches the lungs. This blood looks a darker red colour. The diagram shows it as blue, but the blood is still a red colour even after the oxygen has passed out of the blood into the rest of the body.

So the main job of the heart is to pump blood to every part of the body. The blood carries oxygen and all the food, vitamins and minerals that your body needs to move, think, grow and repair itself. At the same time the blood picks up stuff that your body doesn't need and takes it to those parts of your body that get rid of waste (your lungs, kidneys and liver).

Your blood is pumped all around your body and gets back to your heart in about a minute.

If your heart is healthy it will be able to work for a very long time.

It is up to you to keep your heart healthy.

Your heart will like it if you:

Exercise every dayYou need to exercise your heart by making it work harder for at least 30 minutes a day. Our topics on 'Fitness' and 'Exercise' will show you how.

Eat a healthy diet.Too much fatty food will block up the arteries with fat and your heart will have to work harder and harder just to do its regular job of pumping blood round your body. See our topics in the 'Your food' category to learn about the foods your body needs and what your heart likes.

Drink lots of water every day rather than fizzy drinks.

Make good choices as you grow older. You can choose not to smoke, not to take illegal drugs and not to drink too much alcohol.

I love you with all my heart.She has broken my heart.He died of a broken heart.He wore his heart on his sleeve.She was heartsick.I give you my heart.His heart leaped into his throat.Her heart missed a beat.You have my heartfelt thanks.

Can you think of any more?

I guess that over the years people have noticed that when you have a powerful feeling like fear, anger or excitement, the heart beats faster and so maybe they thought that the heart was where all the strong feelings hang out.

The changes in the heart and blood vessels which cause heart attacks in adults are now starting in many more children and young people. They won't have a heart attack while they are kids, but some of the damage is done then.

It's like a tap which is turned on enough for the water to flow quietly and smoothly. If you turn the tap onto full then the water becomes more turbulent (mixed up) and the sound gets louder.

A heart murmur in young children can happen when the heart beats quite fast. This can happen when the child has a fever or after exercise. The blood flow gets faster and noisier.This is not a health problem.

A heart murmur can be a sign of a health problem when there is a hole between two parts of the heart and the blood is coming from two directions at once, mixing together and causing turbulence and your doctor can hear it.

This type of heart murmur may be a problem. It depends on how much blood is going in the wrong direction.

There may need to be an operation to block off the hole as the blood may not be able to pick up enough oxygen from the lungs to take it all round the body.

This can mean that kids get tired easily and may not be able to do sport or exercise. It can also sometimes mean that the body cannot grow tall and strong.

If you have a heart murmur and the doctor doesn't think that there is a problem then don't worry about it.

It shouldn't stop you from doing anything.

So, get out there and start joining in. Your heart needs the exercise.

We've provided this information to help you to understand important things about staying healthy and happy. However, if you feel sick or unhappy, it is important to tell your mum or dad, a teacher or another grown-up.